Gas Exchange Humans 3 Flashcards Preview

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Flashcards in Gas Exchange Humans 3 Deck (21)
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1
Q

What is the main site of gas exchange in mammals?

A

The site of gas exchange in mammals is the epithelium of the alveoli

2
Q

What are alveoli?

A

Minute air sacs that are within the lungs

3
Q

What is required to ensure a constant supply of oxygen to the body?

A

A diffusion gradient must be maintained at the alveolar surface

4
Q

What is required for efficient transfer of materials?

A
  • Thin partially permeable surfaces

* large surface area to volume ratio

5
Q

What is required to maintain a diffusion gradient?

A

Movement of both the environmental medium and internal medium

6
Q

Why are exchange surfaces located inside an organism?

A

Because they are thin, they can be damaged easily, they are within the organism for protection.

7
Q

Why is mass transport required in mammals?

A
  • Diffusion alone is not fast enough to maintain adequate transfer of oxygen and carbon dioxide along the various components of the lungs.What
  • Breathing is mass transport
8
Q

Why is diffusion of gasses between alveoli and blood very fast?

A
  • Red blood cells are slowed as they pass through pulmonary capillaries, allowing more diffusion time
  • Distance between alveolar air and red blood cells is small, as red blood cells are flattened against the capillary walls
  • Walls of both alveoli and capillaries are very thin, this decreases the distance over which diffusion takes place
  • Alveoli and pulmonary capillaries have a very large surfaces area
  • Breathing constantly ventilates the lungs, and the heart constantly circulates blood around the alveoli, this ensure a steep concentration gradient of the gases to be exchanged is maintained
  • Blood flow through the pulmonary capillaries maintains a concentration gradient
9
Q

Why is there a big surface area for exchanging oxygen and carbon dioxide?

A

There are many alveoli in the lungs

10
Q

What are the alveoli surrounded by?

A

Network of capillaries

11
Q

How does gas exchange occur in the lungs?

A
  • Oxygen from the air moves down the trachea > bronchi > bronchioles and the alveoli
  • This movement occurs down a pressure gradient
  • In the alveoli, the oxygen diffuses across the alveolar epithelium, then the capillary endothelium ending up in the capillary
  • This movement occurs down a diffusion gradient
12
Q

What maintains a concentration gradient?

A

Blood flow through the

capillaries

13
Q

What features of the lungs speed up rate of diffusion?

A
  • Thin Exchange Surface, only one cell thick, short diffusion pathway
  • Large Surface Area, large number of alveoli means there is a large surface area
14
Q

What does lung disease affect?

A
  • Ventilation

* Gas exchange

15
Q

What is tidal volume?

A

Tidal volume is the volume of air in each breath

16
Q

What is ventilation rate?

A

Number of breaths per minute

17
Q

What is forced expiratory volume?

A

Maximum volume of air that an be breathed out in 1 second

18
Q

What is forced vital capacity?

A

Maximum volume of air it is possible to breathe forcefully out of the lungs after a deep breath

19
Q

How does the immune system respond to TB in the lungs?

A

• Immune system cells build a wall around the bacteria in the lungs, to form small hard lumps called tubercles

20
Q

How does TB affect the lung?

A
  • Infected tissue within the tubercles dies, and gas exchange surface is damaged, so tidal volume is decreased
  • TB will also cause fibrosis, which reduces tidal volume even further
21
Q

What are the effects of a reduced tidal volume?

A
• Less air can be inhaled with each breath
•In order to take in enough oxygen, patients have to breathe faster, ventilation rate is increased
Common symptoms include:
• persistent cough
• coughing up blood and mucus
• chest pains
• shortness of breath
• fatigue